Geometry

René Descartes (1596–1650) was educated by the Jesuits, served as a gentleman soldier, and on a winter night in 1619, shut in a stove-heated room in Germany, had the series of dreams that convinced him to rebuild all knowledge from scratch. He spent most of his adult life in the Netherlands, where he could work in peace.

His Discourse on the Method and Meditations made 'I think, therefore I am' the starting point of modern philosophy, and his invention of coordinate geometry joined algebra and geometry for good. Invited to Stockholm by Queen Christina, who wanted lessons at five in the morning, he caught pneumonia and died there in the winter of 1650.